Make new animation from existing fbx of Unity Mecanim tutorial, is it possible ?

Hello, I'm pretty new to Unity and Animation in Unity. I just have a question about creating new animation from the fbx tutorial files. I have some animations from the Mecanim tutorials, but I want to create some more animations, but base on the rigs of the Dude model. Is it possible to do so in Maya (I have installed the fbx plug-ins for Maya) ? And how can I add some constraints (for example the rotation angles, movement of a joint, ...) in that animation ?
PS: I have imported the fbx file and then save the model + rigs as the maya scene, I actually could export to fbx and that fbx animation is readable in unity.

Thank you for your help
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